共查询到20条相似文献,搜索用时 31 毫秒
1.
Hiroshi Kashiwagi Toshikazu Takada Shigeru Obara Eisaku Miyoshi Kimio Ohno 《International journal of quantum chemistry》1978,14(1):13-27
Ab initio LCAO SCF MO calculations are carried out on planar Co-porphine with a basis set of roughly double zeta quality for Co and N and of single zeta quality for C and H. The net charge on Co and N and the overlap population between them are 1.78, ?0.57, and 0.06, respectively, in the 2A1g, state, which is known to be the ground state by experiment. The bonding in this complex is thus largely ionic. The first and second calculated ionization potentials are 6.51 and 6.77 eV, respectively, and are in reasonable agreement with the observed ionization potentials of 6.44 and 6.62 eV for Ni-tetraphenylporphine. CI calculations within the framework of the ligand field theory are also performed. The calculated order of the five lowest states is 4B2g ≈ 4Eg, 4A2g, 2A1g, 4Eg from below and is not in agreement with the semiempirical order of 2A1g ≈ 4B2G, 4A2g, 2Eg, 4Eg determined by Lin. 相似文献
2.
Ab initio electronic structure calculations are reported for low-lying electronic states, 1A1, 1A2, 3A2, 1B1, 3B1, 1B2, and 3B2 of the FNO2 molecule. Geometric parameters for the ground state 1A1 are predicted by MRSDCI calculations with a double-zeta plus polarization basis set. The vertical excitation energies for these electronic states are determined using MRSDCI/DZ+P calculations at the ground-state equilibrium conformation. The oscillator strengths and radiative lifetimes for some electronic states are calculated based on the MRSDCI wave functions. © 1993 John Wiley & Sons, Inc. 相似文献
3.
Japheth F. Rauscher Cathie L. Condron Tanya Beault Susan M. Kauzlarich Newell Jensen Peter Klavins Samuel MaQuilon Zachary Fisk Marilyn M. Olmstead 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(10):i69-i73
Single crystals of the new Zintl phases AIn2P2 [A = Ca (calcium indium phosphide), Sr (strontium indium phosphide) and Ba (barium indium phosphide)] have been synthesized from a reactive indium flux. CaIn2P2 and SrIn2P2 are isostructural with EuIn2P2 and crystallize in the space group P63/mmc. The alkaline earth cations A are located at a site with m symmetry; In and P are located at sites with 3m symmetry. The structure type consists of layers of A2+ cations separated by [In2P2]2− anions that contain [In2P6] eclipsed ethane‐like units that are further connected by shared P atoms. This yields a double layer of six‐membered rings in which the In—In bonds are parallel to the c axis and to one another. BaIn2P2 crystallizes in a new structure type in the space group P21/m with Z = 4, with all atoms residing on sites of mirror symmetry. The structure contains layers of Ba2+ cations separated by [In2P2]2− layers of staggered [In2P6] units that form a mixture of four‐, five‐ and six‐membered rings. As a consequence of this more complicated layered structure, both the steric and electronic requirements of the large Ba2+ cation are met. 相似文献
4.
G. Fritz E. Matern H. Krautscheid R. Ahlrichs J. W. Olkowska J. Pikies 《无机化学与普通化学杂志》1999,625(10):1604-1607
Formation and Structure of the iso -Tetraphosphane P(PtBu2)3: a Molecule with a Planar Three-coordinated P Atom The iso-tetraphosphane P(PtBu2)3 ( 1 ) was obtained by irradiating tBu2P–P=P(Me)tBu2 ( 3 ). 1 forms hexagonal crystals (space group P63/m) with a = 1005,63(8), c = 1621,4(2) pm, Z = 2. The P(PtBu2)3 molecules are arranged in a hexagonally close packed lattice. The four P atoms in each molecule are coplanar with P–P bond distances 219.08(4) pm and P–P–P angles 120°. The observed planar geometry is in accordance with ab initio calculations. 相似文献
5.
Anton I. Smolentsev Dmitry Yu. Naumov 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(2):i17-i19
The structures of tetragonal (P42/ncm) lithium chlorite, LiClO2, and orthorhombic (Cmcm) potassium chlorite, KClO2, have been determined by single‐crystal X‐ray analyses. In LiClO2, the Li atom is at a site of symmetry, while in KClO2, the K atom is at a site with 2/m symmetry. In both compounds, the unique Cl and O atoms are at sites with mm and m symmetry, respectively. The structure of LiClO2 consists of layers of Li+ cations coordinated by ClO2− anions. In contrast, the structure of KClO2 contains pseudo‐layers of K+ and ClO2− ions containing four short K—O distances. The Li+ and K+ cations are surrounded by four and eight chlorite O atoms in tetrahedral and distorted cubic coordination environments, respectively. 相似文献
6.
Rafa Petrus Piotr Sobota 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(4):372-375
The title zinc alkoxide, bis(μ‐2‐ethoxyphenolato)‐κ3O1,O2:O1;κ3O1:O1,O2‐bis[(2‐ethoxyphenolato‐κ2O1,O2)(pyridine‐κN)zinc(II)] toluene hemisolvate, [Zn2(C8H9O2)4(C5H5N)2]·0.5C7H8, crystallizes with two independent complex molecules located on inversion centres and one independent toluene solvent molecule disordered about an inversion centre. The ZnII atoms are six‐coordinated in distorted octahedral geometries with O5N donor sets. The ZnII ions and bridging alkoxide groups are arranged in a diamond Zn2O2 core structure. The guetholate (2‐ethoxyphenolate) ligands adopt two different coordination modes, viz. peripheral chelating and μ2‐bridging. Preliminary investigations of the catalytic activity of the compound in the ring‐opening polymerization of L‐lactide demonstrate rapid and efficient generation of polylactide. 相似文献
7.
The intrinsic dynamic and static nature mc center-ne electron interactions of the σ-type σ(mcc-nee) were elucidated for the Se-Se interactions in dicationic oligomers of Se(CH2CH2CH2)2Se ( 1 (Se, Se)) [ n 2+ (Se, Se): n=1–8], especially for mc≥6, where n 2+ (Se, Se: n=1–8) are abbreviated by n 2+ (n=1–8), respectively. QTAIM dual functional analysis (QTAIM-DFA) was applied to the interactions. Perturbed structures generated using coordinates derived from the compliance constants (Cii) were employed for QTAIM-DFA. Each Se-*-Se in 1 2+ and 2 2+ has the nature of CT-TBP (trigonal bipyramidal adduct formation through CT) and Cov-w (weak covalent), respectively, which supply the starting points of the investigations. The asterisk emphasizes the existence of a bond critical point on the interaction. All Se-*-Se in 3 2+ are classified by the regular closed shell (r-CS) interactions and characterized as CT-MC (molecular complex formation through CT), which are denoted as r-CS/CT-MC, except for the central interaction, of which nature is r-CS/CT-TBP. Most interactions in 4 2+– 8 2+ are r-CS/t-HBwc (typical-HB with covalency) but some are pure-CS/t-HBnc (t-HB with no covalency). The linear Se2n2+ interactions in 2 2+– 8 2+ seem close to those without any limitations, since the nature of Se-*-Se inside and outside of (CH2CH2CH2)2 are very similar with each other. The linear Se2n2+ interactions in 3 2+– 8 2+ are shown to be analyzed as σ(mcc-nee: 6≤mc≤16), not by the accumulated σ(3c–4e). 相似文献
8.
A. Moghimi Sh. Sheshmani A. Shokrollahi H. Aghabozorg M. Shamsipur G. Kickelbick M. Carla Aragoni V. Lippolis 《无机化学与普通化学杂志》2004,630(4):617-624
A novel 1:2 proton transfer self‐associated compound LH2 , (GH+)2(pydc2—), was synthesized from the reaction of dipicolinic acid, pydcH2, (2, 6‐pyridinedicarboxylic acid), and guanidine hydrochloride, (GH+)(Cl—). The characterization was performed using IR, 1H and 13C NMR spectroscopy and single‐crystal X‐ray diffraction. LH2 · H2O crystallizes in the space group C2/c of the monoclinic system and contains eight molecules per unit cell. The unit cell dimensions are: a = 26.480(5)Å, b = 8.055(2)Å, c = 14.068(3)Å. The first coordination complex (GH)2[Cd(pydc)2] · 2H2O, was prepared using LH2 and cadmium(II) iodide, and characterized by 1H and 13C NMR spectroscopy and X‐ray crystallography. The crystal system is triclinic with space group P1¯ with one molecule per unit cell. The unit cell dimensions are: a = 8.5125(7)Å, b = 11.0731(8)Å, c = 13.2404(10)Å. The cadmium(II) atom is six‐coordinated with a distorted octahedral geometry. The two pydc2— units are almost perpendicular to each other. The protonation constants of the building blocks of the pydc‐guanidine adduct, the equilibrium constants for the reaction of pydc2— with guanidine and the stoichiometry and stability of the Cd2+ complex with LH2 in aqueous solution were accomplished by potentiometric pH titration. The solution studies strongly support a self‐association between pydc2— and GH+ with a stoichiometry for the CdII complex similar to that observed for the isolated crystalline complex. In fact, the [Cd(pydc)2]2— complex was found as the most abundant species in solution (> 90 %) at a pH >5. 相似文献
9.
Hui-Hsu Tsai Tracy P. Hamilton Jyh-Hsin M. Tsai Joseph S. Beckman 《Structural chemistry》1995,6(4-5):323-332
Quantum mechanical methods have been applied to thecis-ONOO–-H2O,cis-ONOO–-(H2O)2 andtrans- ONOO–-H2O complexes. Equilibrium geometries, binding energies, net atomic charges and vibrational frequencies are presented for several different arrangements. The MØller-Plessett second-order perturbation (MP2) method predicted shorter hydrogen bonds than the SCF method, but the computed Hartree-Fock (HF) binding energies are similar to counterpoise corrected MP2 values. The geometry changes of ONOO– and water after solvation are examined. The ONOO– and H2O bond length changes follow typical hydrogen bond structural trends, whereas bond angles in ONOO– are unaffected when the hydrogen bond is formed, similar to the conclusions from NO
2
–
-(H2O)
n
HF/6-31G studies and Monte Carlo simulations. Thecis-ONOO–-(H2O)
n
frequencies are compared with the solution Raman spectrum and with calculations on isolated ONOO–. 相似文献
10.
Yoshiki Ozawa Misa Kim Koshiro Toriumi 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(2):146-149
A new one‐dimensional platinum mixed‐valence complex with nonhalogen bridging ligands, namely catena‐poly[[[bis(ethane‐1,2‐diamine‐κ2N,N′)platinum(II)]‐μ‐thiocyanato‐κ2S:S‐[bis(ethane‐1,2‐diamine‐κ2N,N′)platinum(IV)]‐μ‐thiocyanato‐κ2S:S] tetrakis(perchlorate)], {[Pt2(SCN)2(C2H8N2)4](ClO4)4}n, has been isolated. The PtII and PtIV atoms are located on centres of inversion and are stacked alternately, linked by the S atoms of the thiocyanate ligands, forming an infinite one‐dimensional chain. The PtIV—S and PtII...S distances are 2.3933 (10) and 3.4705 (10) Å, respectively, and the PtIV—S...PtII angle is 171.97 (4)°. The introduction of nonhalogen atoms as bridging ligands in this complex extends the chemical modifications possible for controlling the amplitude of the charge‐density wave (CDW) state in one‐dimensional mixed‐valence complexes. The structure of a discrete PtIV thiocyanate compound, bis(ethane‐1,2‐diamine‐κ2N,N′)bis(thiocyanato‐κS)platinum(IV) bis(perchlorate) 1.5‐hydrate, [Pt(SCN)2(C4H8N2)2](ClO4)2·1.5H2O, has monoclinic (C2) symmetry. Two S‐bound thiocyanate ligands are located in trans positions, with an S—Pt—S angle of 177.56 (3)°. 相似文献
11.
Howard C. Haas Ruby L. Macdonald Alan N. Schuler 《Journal of polymer science. Part A, Polymer chemistry》1970,8(5):1213-1226
The polymerization kinetics in water of acrylylglycinamide (AG) initiated by K2S2O8 was studied over the temperature range 40.0 to 60.0°C. Monomer concentration was varied from 7.8 × 10?3 to 31.2 × 10?3M and catalyst from 1.85 × to 11.10 × 10?5M. The rate expression is ?d[M]/dt = Rp, = k1.22[K2S2O8]0.5[M]1.22, and the overall empirical rate constant, k1.22 = 1.14 × 1011e?15,800/RT 1.0.72 mole?0.72 min?1. To explain the dependence on monomer, a kinetic scheme which includes a bimolecular reaction (k2) between monomer and initiator is suggested. The simplified expression which describes the initial rate of polymerization is: ?d[M]/dt = Rp, = k4(2[I]/k5)1/2[M](k1 + k2[M])1/2, where k1, k2, k4 and k5 are rate constants for S2O8 = decomposition, a bimolecular reaction between monomer and initiator, propagation, and termination, respectively. Individual bimolecular rate constants are expressed in liter/mole-min. The equation predicts a dependence on monomer concentration between 1.0 and 1.5 with 1.5 being approached a t high monomer concentrations. Plots of RP2/[M]2 versus [M] are linear, as predicted by the postulated reaction route and values for k2 and k4/k51/2 were obtained from the slopes and intercepts of these plots. The temperature dependence of the bimolecular monomer-initiator reaction is k2 = 5.19 × 1021e?36,000/RT. Instead of the usual behavior, the k4/k51/2 ratio was found to decrease with temperature and the difference of activation energies, (E4 ? E5/2), is ?1.50 kcal. The temperature dependence of the propagation to square root of the termination rate constant ratio is k4/k51/2 = 6.16e1500/RT. These rather unusual results may be related to the ability of AG polymers in water to form thermally reversible gels; even above the gel melting points, the polymers are considerably aggregated in solution. This would tend to make the bimolecular termination reaction more temperature dependent and also account for the high values (59–69) for the k4/k51/2 ratios. For similar temperatures, the overall rate constants for AG are approximately four times those for acrylamide. 相似文献
12.
Xiongfa Yang Yina Yang Qian Shao Linlin Yang Xilin Hua Guoqiao Lai 《Phosphorus, sulfur, and silicon and the related elements》2013,188(4):495-505
Abstract An environmentally benign hydrolysis of methylphenyldiethoxysilane (MePhSi(OEt)2) catalyzed by a rare earth superacid catalyst SO 2? 4 /TiO2/Ln3+ has been investigated. The hydrolysis rates decrease in the order SO 2? 4 /TiO2/Nd3+ > SO 2? 4 /TiO2/Y3+ > SO 2? 4 /TiO2/Sm3+ > SO 2? 4 /TiO2. The hydrolysis of MePhSi(OEt)2 is a first-order reaction with respect to the concentration of MePhSi(OEt)2, and the hydrolysis rate constant increases with increasing temperature. The activation energy E a and the pre-exponential factor for this hydrolysis catalyzed by SO 2? 4 /TiO2/Nd3+ have been determined as 322.50 kJ mol?1 and 7.12 × 1041 s?1, respectively. The products of the hydrolysis are oligomers of polymethylphenylsiloxane. The mechanism of MePhSi(OEt)2 hydrolysis is also discussed. 相似文献
13.
InIII-Phthalocyanines: Synthesis, Properties, and Crystal Structure of Tetra(n-butyl)ammonium-cis-di(nitrito-O,O')phthalocyaninato(2–)indate(III) [In(Cl)Pc2?] reacts with (nBu4N)NO2 in acetone yielding green-blue (nBu4N)cis[In(NO2)2Pc2?], which crystallizes in the monoclinic space group P21/n (No. 14). Both nitrite anions are coordinated as chelating nitrito-O,O'(NO2) ligands to InIII in cis-geometry. Consequently InIII is octa-coordinated within a distorted “quadratic” antiprism and directed towards the Pc2?-ligand. One of the NO2 ligands has equivalent N? O bonds similar to free nitrite, while the other has asymmetric N? O bonds. Both (In,O,N,O) rings are approximately planar with a dihedral angle of 80°. The Pc2? ligand is distorted in an asymmetrically convex manner. Partially overlapping pairs of Pc2? ligands related by an inversion center form double layers, which are separated by layers containing the (nBu4N)+ cations. The cyclic voltammogram shows three electrode processes, which are assigned to the redox pairs: Pc3?/Pc2? (?0.94 V) < InI/InIII (-0.78 V) < Pc2?/Pc? (0.64 V). The UV-VIS-NIR spectra and vibrational spectra are discussed. 相似文献
14.
Henk van der Poel Gerard van Koten David M. Grove Paul S. Pregosin Karl A. Ostoja Starzewski 《Helvetica chimica acta》1981,64(4):1174-1182
195Pt-, 31P- and 15N-NMR. data are presented for [PtCl2 (t-Bu 15N?CH? CH?15N (t-Bu)) (η2-styrene)] ( 1 ), trans-[{PtCl2 (PBu3)}2 (t-Bu 15N?CH? CH?15N (t-Bu))] ( 2 ), trans-[PtCl2 (t-Bu 15N?CH? CH?15N (t-Bu)) (PBu3)] ( 3 ) and various complexes of the type trans-[PtCl2 (N-ligand) (PBu3)]. In solution the gross structural features of 1 and 2 are shown to be in agreement with those found in the solid state; namely, 1 contains five-coordinate Pt and 2 is dinuclear. In 3 Pt is four-coordinate with only one N-atom of the diimine ligand being coordinated at ?50° in CD2Cl2. The NMR. data for 2 and 3 are compared with those of trans-[PtCl2 (N-ligand) (PBu3)] (N-ligand = pyridine, 2, 6-dimethylpyridine, (15N)-hexylamine, (15N)-t-butylamine and (15N)-aniline) and are discussed in terms of the donor and acceptor properties of the N-ligands. 相似文献
15.
Masood Parvez Shaun T. Mesher Peter D. Clark 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(5):574-576
The structure of 2,5‐bis(methylthio)‐1,4‐benzoquinone, C8H8O2S2, is composed of an essentially planar centrosymmetric benzoquinone substituted with two methylthio groups. The important bond distances are S—Csp3 1.788 (2) and S—Csp2 1.724 (2) Å, and the two Csp2—Csp2 distances are 1.447 (3) and 1.504 (3) Å, which differ significantly. There are short S?S interactions of 3.430 (1) Å and Csp2—H?O‐type contacts forming a dimeric motif with graph set R22(8). The structure of 2‐methyl‐3‐(methylsulfonyl)benzo[b]thiophene, C10H10O2S2, is composed of an essentially planar benzothiophene moiety substituted with methyl and methylsulfonyl groups. The mean values of the important bond distances are endocyclic S—Csp2 1.734 (3), S=O 1.434 (4) and C—Caromatic 1.389 (10) Å. The exocyclic S—Csp2 and S—Csp3 distances are 1.759 (4) and 1.763 (5) Å, respectively. 相似文献
16.
Jozef Lengyel Viktoriya Poterya Michal Fárník 《Journal of mass spectrometry : JMS》2015,50(3):643-649
The proton transfer (PT) and other intraclusters reactions occurring after electron ionization of aniline clusters (PhNH2)N are investigated by the time‐of‐flight mass spectrometry. The mass spectra are recorded for different expansion conditions leading to the generation of different cluster sizes. Several fragment ions are shown to originate from intracluster reactions, namely, [Ph]+, [PhNH3]+ and [Ph–N–Ph]+. Reaction schemes are proposed for these ions starting with the PT process. The mass region beyond the monomer mass is dominated by cluster ions (PhNH2)n+ accompanied by satellites with ±H and +2H. In experiments with deuterated species, new fragment ions are identified. The aniline isotopomer d5‐PhNH2 yields the fragment ions (PhNH2)n?(N–Ph–NH2)+. Analogical series is observed in experiments with d7‐PhND2, and additional fragments occur corresponding to (PhND2)n?(D2N–ND–Ph–ND–ND2)+ ions. The possible reaction pathways to these ions and the unusual isotope effects are discussed. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
17.
Z.-L. Cai 《Journal of computational chemistry》1994,15(3):346-350
The equilibrium geometries, excitation energies, force constants, and vibrational frequencies of the low-lying electronic states X2B1, 2A1, 2B2, and 2A2 of the PF2 radical have been calculated at the MRSDCI level with a double zeta plus polarization basis set. Our calculated geometry, force constants, and vibrational frequencies for the X2B1 state are in good agreement with experimental data. The electronic transition moments, oscillator strengths for the 2A1 → X2B1 and 2A2 → X2B1 transitions, and radiative lifetimes for the 2A1 and 2A2 states are calculated based on the MRSDCI wave functions. © 1994 by John Wiley & Sons, Inc. 相似文献
18.
Synthesis, Crystal Structure, Vibrational Spectra, and Normal Coordinate Analysis of cis‐ and trans‐(n‐Bu4N)2[PtF2(ox)2] and (n‐Bu4N)2[PtF4(ox)] By treatment of trans‐(n‐Bu4N)2[PtCl2(ox)2] and (n‐Bu4N)2[PtCl4(ox)] with XeF2 in propylene carbonate cis‐ and trans‐(n‐Bu4N)2[PtF2(ox)2] ( 1 , 2 ) and (n‐Bu4N)2[PtF4(ox)] ( 3 ) are formed which have been isolated by ion exchange chromatography on diethylaminoethyl cellulose. The crystal structure of trans(n‐Bu4N)2[PtF2(ox)2] ( 2 ) (tetragonal, space group P42/n, a = 15.5489(9), b = 15.5489(9), c = 17.835(1)Å, Z = 4) und Cs2[PtF4(ox)] ( 3 ) (monoclinic, space group C2/m, a = 14.5261(7), b = 6.2719(4), c = 9.6966(9)Å, β = 90.216(8)°, Z = 4) reveal complex anions with nearly D2h and C2v point symmetry. The average bond lengths in the symmetrical coordinated axes are Pt—F = 1.93 ( 2 , 3 ) and Pt—O = 1.987 ( 2 ) and in the F•—Pt—O′‐axes Pt—F• = 1.957 and Pt—O′ = 1.977Å ( 3 ). The oxalato ligands are nearly planar with a maximum displacement of the ring atoms of 0.05 ( 2 ) und 0.01Å ( 3 ) to the calculated best planes. In the vibrational spectra the symmetric and antisymmetric PtF stretching vibrations are observed at 583 and 586 ( 2 ) and 576 and 568 cm—1 ( 3 ). The PtF• modes appear at 565 and 562 ( 1 ) and 560 cm—1 ( 3 ). The PtO and PtO′ stretching vibrations are coupled with internal modes of the oxalato ligands and appear in the range of 400—800 cm—1. Based on the molecular parameters of the X‐ray determinations ( 2 , 3 ) and estimated data ( 1 ) the IR and Raman spectra are assigned by normal coordinate analysis. The valence force constants are fd(PtF) = 3.55 ( 2 ) and 3.38 ( 3 ), fd(PtF•) = 3.23 ( 1 ) and 3.20 ( 3 ), fd(PtO) = 2.65 ( 1 ) and 2.84 ( 2 ) and fd(PtO′) = 2.97 ( 1 ) and 3.00 mdyn/Å ( 3 ). Taking into account increments of the trans influence a good agreement between observed and calculated frequencies is achieved. The NMR shifts are δ(195Pt) = 8485 ( 1 ), 8597 ( 2 ) and 10048 ppm ( 3 ), δ(19F) = —350 ( 2 ) and —352 ( 3 ) and δ(19F•) = —323 ( 1 ) and —326 ppm ( 3 ) with the coupling constants 1J(PtF) = 1784 ( 2 ) and 1864 ( 3 ) and 1J(PtF•) = 1525 ( 1 ) and 1638 Hz ( 3 ). 相似文献
19.
Direct thermally induced reactions between rare earth metals (Ln = Y,Ce, Dy, Ho, and Er) activated by Hg metal and 3,5‐diphenylpyrazole (Ph2pzH) or 3,5‐di‐tert‐butylpyrazole (tBu2pzH) yielded either homoleptic complexes [Lnn(R2pz)3n] or a heteroleptic complex [Ln(Ph2pz)3(Ph2pzH)2] From Ph2pzH, [Ce3(Ph2pz)9], [Dy2(Ph2pz)6], [Ho2(Ph2pz)6], and [Y(Ph2pz)3(Ph2pzH)2] were isolated. The first has a bowed trinuclear Ce3 backbone with two η2 pyrazolate ligands on the terminal metal atoms and one on the middle, and bridging by both μ‐η2:η2 and μ‐η2:η5 ligands between the terminal and the central Ce atoms. Although both the Dy and Ho complexes are dinuclear, the former has the rare μ‐η2:η1 bridging whilst the latter has μ‐η2:η2 bridging. Thus the dysprosium complex is seven‐coordinate and the holmium is eight‐coordinate, in contrast to any correlation with Ln3+ ionic radii, and the series has a remarkable structural discontinuity. The heteroleptic Y complex is eight coordinate with three chelating Ph2pz and two transoid unidentate Ph2pzH ligands. From tBu2pzH, dimeric [Ln2(tBu2pz)4] (Ln = Ce, Er) were isolated and are isomorphous with eight coordinate Ln atoms ligated by two chelating terminal tBu2pz and two μ‐η2:η2 tBu2pz donor groups. They are also isomorphous with previously reported La, Nd, Yb, and Lu complexes. 相似文献
20.
《Journal of Coordination Chemistry》2012,65(4):449-456
The complex fac-(η2-C60)(η2-dppe)Cr(CO)3 (dppe?=?1,2-bis(diphenylphosphino)ethane and C60?=?[60]fullerene) reacts with piperidine (pip) to produce fac-(η2-C60)(η1-pip)2Cr(CO)3. The reactions are first order with respect to [?fac-(η2-C60)(η2-dppe)Cr(CO)3] under flooding conditions where [pip]???[?fac-(η2-C60)(η2-dppe)Cr(CO)3]. The pseudo-first order rate constant values (k obsd) are [pip]-dependent. Curved (upward) plots of k obsd versus [pip] and linear plots of k obsd versus [pip]2 indicate that the piperidine-assisted dppe displacement from fac-(η2-C60) (η2-dppe)Cr(CO)3 is second order with respect to [pip]. The proposed mechanism involves a [60]fullerene-stabilized intermediate. 相似文献